[TenTec] QSK or not?

Bob McGraw - K4TAX RMcGraw at Blomand.net
Mon Mar 17 20:26:39 EDT 2014

The biggest problem, as I understand, comes from operators using a non QSK 
qualified amp in a QSK mode.  At this point one can expect relay failure due 
to hot switching.

As most amps do have the provision for monitoring SWR I suggest monitoring 
the SWR indication for an indication of hot switching.  After tune up 
typically one will have low SWR..  If during keying one observes a higher 
SWR value they can be assured that hot switching is taking place within the 
amp.  If this is the case, be assured the relays are taking a beating 
electrically and will likely soon need attention.

Do note the same situation when operating VOX.  Most radios provide some 
degree of key-up delay when in CW but there is typically no delay during SSB 
operation.  Thus when the voice activates the VOX there is RF applied to the 
amp without any delay.  I find this to be a sure bet for realy hot 

Bob, K4TAX

----- Original Message ----- 
From: "GARY HUBER" <glhuber at msn.com>
To: "TenTec Reflector" <tentec at contesting.com>
Sent: Monday, March 17, 2014 10:39 AM
Subject: [TenTec] QSK or not?

I operate QSK and have the past thirty years using TenTec equipment.

One reason given by others for not running QSK is that the relays wear out 
sooner in the transceiver and amplifier.

from http://www.ad5x.com/images/Presentations/QSKals500als600RevA.pdf

How Long will the Relays Last?
What kind of life can you expect from the relays? The relay life is 
specified at 100
million operations minimum at 36,000 operations/hour. The service life 
increases as the
operations/hour decreases. So let’s use the standard PARIS text that is used 
determining code speed.

PARIS has 10 dits and 4 dahs = 14 relay operations/minute at 1 WPM.

Assuming an average of 25WPM code speed, you would have 360 relay operations 
minute. So, 100 million operations = 4630 hours. Now you normally operate 
transmitting and 50% receiving during a QSO, so your relay operating time 
double to 9260 hours. There are 8760 hours/year, which means you could 
operate 1.057
years at 25 WPM before the relays exceeded their lifetime spec – IF you 
operate 24
hours/day! But when you operate, you are probably listening more like 75% of 
the time
and in a QSO 25% of the time. So this says that your relay operating life 
will be over 4-
years if you operate 24 hours/day. So what do you normally average in 
time/day? I bet it is not more than about an hour/day. But let’s say you 
average 4-
hours/day of operation (i.e. you are not married and have no kids, you don’t 
shop or eat
or sleep much, and you don’t hold a full-time job). So the relay life will 
extend to about
25 years! The bottom line - Don’t worry about wearing out the relays anytime 

73 ES DX,
Gary – AB9M    -...-.-
TenTec mailing list
TenTec at contesting.com

More information about the TenTec mailing list